1. Field of the Invention
The invention disclosed in this specification relates to a polymerizable monomer compound, a liquid crystal composition including the polymerizable monomer compound, a liquid crystal display device including the polymerizable monomer compound, and manufacturing methods thereof.
2. Description of the Related Art
In recent years, flat panel displays have been put to practical use and have been substituted for conventional displays using cathode-ray tubes. The flat panel displays include liquid crystal display devices which have liquid crystal elements, EL display devices which have electro luminescent elements (EL elements), plasma displays, and the like, and they come into competition in the market. Liquid crystal display devices establish a position of superiority by overcoming disadvantages and suppressing production cost with use of a variety of techniques.
As a constituent of a liquid crystal composition used for a liquid crystal display device, a polymerizable monomer compound is used. For example, polymer dispersed liquid crystal (PDLC) or polymer network liquid crystal (PNLC) has a structure in which liquid crystal grains are dispersed in a polymer layer which forms a polymer network, and a white image (a bright image) is displayed using scattered light by liquid crystal. A polymerizable monomer compound is used as a material of the polymer layer.
Further, in the case where a display mode using liquid crystal exhibiting a blue phase is employed as a display mode of liquid crystal, a polymerizable monomer compound is used in some cases. It has been reported that a liquid crystal composition which includes a polymerizable monomer compound and a liquid crystal material exhibiting a blue phase is subjected to polymer stabilization treatment by which a polymerizable monomer compound is polymerized, so that the temperature range where a blue phase is exhibited is expanded (for example, see Patent Document 1).
Furthermore, a polymerizable monomer compound is also used as a material of an optical film which is provided to, for example, achieve a wide, viewing angle and improvement in contrast in a display portion of a liquid crystal display device (for example, see Patent Document 2).